The present invention relates to an absorbent article, such as a sanitary napkin, a panty liner or an incontinence protector, which is intended to be carried in the crotch region of the wearer inside the wearer""s panties or pants, said article having a generally elongated shape with two long sides, two short sides, two end-portions, a central portion located between the end-portions, a liquid-permeable casing sheet or top sheet which is intended to lie proximal to the wearer""s body in use, a liquid-impermeable casing sheet or backing sheet intended to lie distal from the wearer""s body in use, and between said sheets a drainage sheet and an element which forms a hump on the side of the article that lies proximal to the wearer""s body in use, as seen in a direction from the liquid-permeable casing sheet towards the liquid-impermeable casing sheet.
Conventional absorbent articles of the aforesaid kind are generally flat. Consequently, when the lower abdomen of the female carrier is not flat problems can occur when donning and wearing such articles. In such cases, abutment of the article with the wearer""s body is not of the best and if gaps occur between product and the user""s body there is a serious risk that body fluid will leak past the long side-edges of the article. Such leakage is particularly undesirable, since it is very liable to soil the wearer""s clothes. Rearward leakage is a particular problem in this respect, which normally occurs when the user lies down, for instance at night.
With the intention of solving this problem, it has been proposed to provide the absorbent articles with a pre-formed hump. Absorbent articles that include humps are described in EP-A-0 419 434, among others. The intention of providing absorbent articles with pre-formed humps is to create contact with the genitals of the wearer in use. Discharged body fluids can be caught immediately on leaving the wearer""s body and will be absorbed immediately by the article, without running out over its surface and over the long edges of the article.
Another drawback with flat articles is that when the article is used, it is influenced by forces exerted by the wearer""s thighs for instance, so as to wrinkle the product and/or cause the long edges of the product to fold over the liquid-permeable surface thereof. A wrinkled surface and/or inwardly folded long edges of the product will significantly reduce the liquid-permeable surface and in many cases to a size that is insufficient to capture all liquid discharged by the wearer at one time, wherewith leakage may occur.
A conventional way of creating a hump is simply to provide a large amount of absorbent material in the absorbent pad within the area where the hump is desired, and form the hump from this excess material. Humps are most often formed from an absorbent material referred to as cellulose fluff pulp, in other words defibred pulp from, e.g., thermomechanical pulp, chemithermomechanical pulp, or chemical sulphite pulp or sulphate pulp. Such a material, however, is not stable when wet, and consequently a hump comprised of such material will collapse and lose its shape when wet. In order to obtain a hump consisting of cellulose fluff pulp and having sufficient height whilst the article is in use, it is necessary to use so much cellulose fluff pulp in the production of the hump as to cause the hump to be felt uncomfortable by the wearer. Another problem that occurs with an article constructed in accordance with the above description is that control of the liquid dispersion capacity of the article in the z-direction is lost, because the article loses its shape when wetted. It is also known to produce an article which includes a hump that faces towards the wearer, by placing a moulding or shaping element on top of the absorbent core. One drawback in this respect is that the hump results in inertia in liquid transportation down into the product, due to the fact that the shaping element must be filled with liquid before it releases the liquid to the underlying absorption core, said core having a strong liquid suction and absorbing effect and also a liquid retaining absorption effect. Earlier patent documents have also proposed the use of foam material in providing the hump. A problem with the use of foam material in the hump resides in the difficulties in achieving a foam structure that has sufficiently open pores to obtain effective ingress of liquid into the structure, at the same time as the material shall have great ability in retaining the liquid in its structure without liquid being forced therefrom when subjected to load by the wearer, for instance when the wearer sits down. A hump can also be provided on the upper side of the article, by providing a planar article with a shaping element that takes a convex shape in relation to the wearer when the sides of the article in the region of the crotch are subjected to greater loads from the wearer""s thighs. The drawback with this solution is that the shaping element returns to its original planar state immediately the wearer does not subject the sides of the article to pressure, e.g. when she stands with her legs apart or sits in a xe2x80x9clotus positionxe2x80x9d, and also because it is difficult to produce a shape that corresponds essentially to the body shape of the wearer, solely by flexural deformation.
An absorbent article of the kind described in the introduction is known from EP-A1-0 768 072. However, in this case, the hump-forming element also constitutes the element that shall absorb and store discharged liquid and comprises a compressible, resilient and wet-stable material.
The object of the present invention is to provide an absorbent article of the aforesaid kind which conforms well to the wearer""s body, makes the risk of leakage slight, and enables the hump-forming element to be manufactured from both absorbent material that is not wet-stable and non-absorbent material.
This object is achieved in accordance with the invention with an article of the kind described in the introduction that is characterised by an absorbent layer disposed between the drainage layer and the hump-forming element, wherewith the absorbent layer has smaller capillaries than the drainage layer and that part of the hump-forming element that lies against the absorbent layer.
The drainage layer, which has a lower density and therewith larger capillaries than the underlying absorbent layer, is placed on top of the absorbent layer, therewith contributing towards the rapid ingress of liquid in the z-direction down to the absorbent layer, in other words there is obtained a capillary size gradient with large capillaries in the drainage layer and smaller capillaries in the absorbent layer, meaning that the absorbent layer will leach/draw liquid out from the drainage layer. As a result of the difference in the size of the capillaries between the absorbent layer material and the material of the hump-forming element (the absorbent layer has smaller capillaries than the hump-forming material) no natural dispersion of liquid to the underlying hump-forming element will take place, since the capillary forces act in the opposite direction, i.e. the absorbent layer leaches out any liquid present in the hump-forming element. This means that the hump-forming element need not necessarily include material that retains its shape in a wet state, as this element will not be subjected to large amounts of liquid. The construction of the article in this manner makes accessible a wide selection of hydrophobic materials, hydrophilic materials or mixtures thereof for use as hump-forming elements.
The absorbent layer may conveniently extend beyond the contour line of the hump-forming element, but inwardly of the contour line of the drainage layer. The drainage layer is placed on top of the absorbent layer because rapid ingress of the liquid into the hump is desired, wherewith the surface that lies proximal to the wearer in use will be drier and more comfortable than might otherwise be the case, and also results in a softer and more comfortable hump. The advantage gained by virtue of the surface of the absorbent layer being larger than the hump-forming element is that the layer can be draped over the hump-forming element and therewith together create a hump on the upper side of the article while creating an absorbent fluid receiving area around the hump base for dealing with liquid that is too fast to be absorbed on the top of the hump but runs down towards the hump base. There is thus created a safety zone around the hump.
According to one particularly preferred embodiment of the invention, the hump has an elongate form and narrows in a direction towards the end parts of the article and, when seen from one short side of the article, will preferably have a triangular cross-section with a larger width at the base than at the top, preferably with a length of between 20 mm and 140 mm and a height between 5-20 mm. It has been found that such an embodiment imparts good comfort qualities to the article; the article has a less tangible thickness and is less uncomfortable, and is experienced visually as being smaller and more comfortable to wear. The hump will preferably have a generally triangular cross-section, in other words when seen from one short side of the absorbent article, the hump will have a greater width at its base than at its top, where the top is directed towards the side with the liquid receiving casing sheet and the base directed towards the rear side of the article. One advantage afforded by a hump that has the cross-section described above is that there is achieved good body adaptation, where the top of the hump is able to meet the body between labia without discomfort. The hump-forming element is conveniently comprised of a resilient material, that need not necessarily be absorbent.
According to a first embodiment, the hump-forming element is comprised of a non-absorbent material.
According to another embodiment, the hump-forming element is comprised of an absorbent material.
According to still another embodiment, the hump is disposed essentially in the central part of the article.
According to a preferred embodiment of the invention, the hump-forming element extends also over large parts of the end-portions of the article, said end-portions being turned rearwards when the article is used, which results in a corresponding, longitudinally extending hump that projects out from the plane of the article on that side of said article that is intended to lie proximal to the wearer in use.
According to another embodiment, the hump terminates short of the region of the front end-portions of the article, so that the article will conform better to the curvature of the wearer""s body. This product is intended to be turned so that the hump will abut the crotch region of the wearer and so that the hump will continue rearwards between the wearer""s buttocks, therewith contributing towards effective sealing, primarily when the wearer lies down, for instance to sleep.
According to another preferred embodiment of the invention, the absorption layer and the drainage layer have a longitudinally extending cut along the longitudinal center line of the article, such that the underlying hump-forming element will project up through the absorption layer. Because the hump-forming element will come into contact with moisture during use, it is beneficial for at least that part of the hump-forming element which lies against the overlying absorption layer, i.e. the surface areas of the hump-forming material, to be comprised of a material that has larger capillaries than the absorption layer, and preferably a somewhat retained shape in both dry and wet conditions, and that the portion of the hump-forming element that projects up through the cut in the absorption layer and the drainage layer also has larger capillaries than the drainage layer. This results in an acquisition area that has an extra large capillary structure in the region of the cut up onto the hump. The bordering absorption layer then drains off the acquisition area and disperses the liquid further within the absorption layer. This embodiment is particularly favourable in those cases when a large volume of liquid is discharged within a short period of time.
The longitudinal cut in the absorption layer and the drainage layer also enables the material to be draped more readily around the hump-forming element, therewith facilitating the provision of a more pointed hump apex.
According to still another embodiment of the invention, the absorption layer and the drainage layer include a longitudinal cut in accordance with the aforegoing, wherewith the end parts of the cut have been joined with a further cut that defines between itself and the imaginary extension of the longitudinal cut an angle xcex3 corresponding between 10xc2x0-90xc2x0.
In one variant of the above-mentioned embodiments that include a longitudinal cut in the absorption body and the drainage layer, the density of the hump-forming element increases successively downwards, i.e. away from the absorption layer in a direction towards the liquid-impermeable casing sheet. There is obtained in this way an acquisition area of extra large pore stricture in the region of the cut up on the hump, and part of the liquid will be drained out by the bordering absorption layer and dispersed further within said absorption layer, while part of the liquid will be dispersed and stored within the hump-forming element. Such an embodiment is particularly appropriate when large volumes of liquid are expected to be discharged instantaneously.